The present invention relates to generally a color television camera, and more particularly a single-tube color television camera.
Of various types of color television cameras, there has been known the so-called single-tube color television cameras of the type in which the color components split by a stripe type optical color filter are converted into electrical signals by a single camera tube in a time division manner. Such a color television camera has the advantages that it is compact in size, light in weight and inexpensive to manufacture, but its resolution is unsatisfactory compared with the three-tube television cameras. In general, the conventional optical filters include a large number of black stripes as a means for generating the reference signal used for the color signal separation. Therefore, the sensitivity as well as the resolution are further decreased. To overcome these problems, there has been devised and demonstrated a color television camera tube of the type in which two comb-shaped electrodes are formed as means for generating the reference signal for the color signal separation, but the construction of the electrodes of the television camera tube and its associated circuits is very complex, resulting in an increased cost.
To overcome the above undesirable features, there has been devised and demonstrated a frequency separation type color television camera of the type disclosed in Japanese Pat. Publication No. 8699/1970. This camera eliminates the use of means for generating the reference signal for color signal separation. It uses the combination of a first color splitting filter of the type consisting of a large number of transparent stripes and yellow stripes which are vertically and alternately arrayed, and a second color splitting filter of the type consisting of a large number of transparent stripes and cyan stripes which are transversely and alternately arrayed. The color signal components derived by passing the output from the camera tube through a pre-amplifier and a band-pass filter are added to and substracted from the signal obtained by delaying the color signal components by 1H; that is, one horizontal scanning time (about 6.mu.sec.) and the outputs from the adder and substractor are detected, so that the red and blue primary color signals may be obtained.
The fundamental frequencies of the color signal components are very high and of the order of few MHz. Therefore, from the standpoint of linearity of the deflection system and the electrical stability of the 1H delay circuit, various difficulties are encountered in practice and circuits with complex construction are required in order to delay the color signal component by 1H; so as to generate the delayed signal which is out of phase by 180.degree. from the original signal.